Owner’s manual
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Should I use 87 or 89 gas for lawn mower?
Use 87 octane (regular unleaded) in your Craftsman 917378500 gas walk-behind lawn mower. Our owner’s manual specifies fresh, clean, regular unleaded gasoline with a minimum of 87 octane; using 89 is unnecessary for normal operation. See the fuel section in the owner's manual.
Fuel choice for the Craftsman 917378500
For this mower, the key is fresh fuel and correct storage, not higher octane.
- Use regular unleaded, 87 octane or higher.
- Do not mix oil with gasoline.
- Fill the tank only to the bottom of the filler neck (do not overfill).
- Buy fuel you can use within 30 days to keep it from going stale.
- Wipe up spilled fuel and keep gasoline away from ignition sources.
Ethanol and storage tips (prevents hard starting)
Alcohol-blended fuels (gasohol, ethanol, methanol) can pull in moisture during storage, which can lead to fuel separation and fuel-system damage over time. If the mower will sit 30 days or longer, we recommend emptying the fuel system.
Storage checklist
- Run the engine until the tank is empty.
- Keep running until the carburetor and fuel lines are empty.
- Refill with fresh fuel at the start of the next season.
- Follow the storage steps in the owner's manual.
Quick comparison: 87 vs 89 for this mower
| Fuel at the pump | Works in Craftsman 917378500? | When to use it |
|---|---|---|
| 87 octane (regular) | Yes | Everyday mowing (recommended) |
| 89 octane (mid-grade) | Yes | Only if 87 is unavailable; no performance benefit expected |
Why it matters
Using the correct fuel helps prevent hard starting, rough running, and carburetor issues. For small engines like this Craftsman mower, fuel freshness and proper storage typically make a bigger difference than stepping up from 87 to 89 octane.
Last updated: February 2026
What are the common problems with CRAFTSMAN lawn mowers?
Common problems on the Craftsman 917378500 gas walk-behind lawn mower include no-start conditions (spark plug wire off, bad spark plug, control bar issues, fuel valve OFF), loss of power from airflow or deck buildup, and drive problems caused by worn belts or pulleys. Use the troubleshooting chart in the owner's manual to match symptoms to fixes.
Most common symptoms and what usually causes them
- Won’t start: spark plug wire disconnected, bad spark plug, control bar released/defective, fuel valve OFF (if equipped)
- Loss of power: dirty air filter, grass and debris buildup under the deck, cutting too much grass at once, oil level too high
- Starter rope hard to pull: blade dragging in grass, flywheel brake engaged when control bar is released, bent crankshaft, damaged blade adapter
- Hard to push: grass too high, cutting height too low, grass catcher overfull, deck packed with clippings
- Loss of drive or slow self-propel: worn or stretched drive belt, worn drive pulley, drive cover damage, cable out of adjustment
Quick checks we recommend before buying parts
- Disconnect the spark plug wire before inspecting the blade area.
- Confirm the control bar is held fully against the handle during starting.
- Check fuel shutoff position (if your mower has a fuel valve).
- Clean packed grass from under the deck and verify the cutting height is not set too low.
- Inspect the blade and blade adapter for looseness or damage.
Parts that commonly solve these issues (when worn or damaged)
If you find wear or damage during inspection, these model-matched parts are common fixes:
- Drive issues: lawn mower ground drive belt, 3/8 x 33-9/16-in 532169778, drive pulley 532443262
- Vibration, poor cut, or rope hard to pull after impact: premium blade 532406706, lawn mower blade adapter 532418373
- Control and speed complaints: lawn mower throttle cable 532168552
Symptom-to-part cheat sheet
| Symptom | Most likely area | Example part on this model |
|---|---|---|
| Self-propel won’t move | Belt and pulley drive | 532169778, 532443262 |
| Cuts uneven or vibrates | Blade and adapter | 532406706, 532418373 |
| Speed control feels wrong | Throttle cable linkage | 532168552 |
Why it matters
Catching these problems early prevents bigger failures. For example, mowing with a loose blade or damaged blade adapter can make the starter rope hard to pull and can quickly worsen cutting performance.
Last updated: February 2026
What model number is the CRAFTSMAN 917378500?
The model number for this Craftsman gas walk-behind lawn mower is 917.378500 (often written without the dot as 917378500). You can confirm it on the mower’s model tag and in the 917378500 owner's manual.
Where to find the model number on the mower
Most Craftsman walk-behind mowers list the model number on a label or stamped tag. Check these common spots:
- Rear of the deck near the discharge chute
- Top of the deck behind the engine
- Near the rear wheel height adjuster area
- On the handle support bracket area
- Inside the rear door area (bagging models)
Why the dot matters (917.378500 vs 917378500)
Both formats refer to the same mower. The manual and diagrams commonly show the dotted format.
| Format you may see | What it means | Use it for |
|---|---|---|
| 917.378500 | Same model number with a dot | Manuals, diagrams, parts lists |
| 917378500 | Same model number without punctuation | Ordering parts, searches |
Why it matters for parts lookup
Using the exact model number helps us match the correct diagrams and parts for your mower’s drive system, blade, and handle controls.
- Ensures the correct blade and blade adapter fit your deck
- Helps match drive components like the ground drive belt
- Prevents ordering the wrong hardware (nuts, washers, E-rings)
Examples of model-matched parts on this page
If you are shopping for common wear items, these are examples of parts listed for model 917378500:
- Premium blade 532406706
- Lawn mower blade adapter 532418373
- Lawn mower ground drive belt, 3/8 x 33-9/16-in 532169778
Quick tip: confirm before ordering
Match the model tag to 917.378500 and then compare the part description in the diagrams to what you are replacing. This is especially important for drive and height-adjust parts.
Last updated: February 2026
